Discussion in 'Members' Systems' started by Ludi, May 13, 2012.
Thank you! I will try to post pictures as the work progresses.
A Media Luna is a rock construction meant to stop erosion at the top or bottom of gullies. I built one this morning at the top of a small gully forming where water runs off our back field:
Functional and pretty! Great stuff Ludi.
I like the Argentine media-lunas. Like small sweet croissants filled with custard and/or dulce de leche. Yummm! Also very pretty and functional
Very cool Ludi, and inspiring! I like the PDF too.
Can you clarify something for me, Ludi?
Sad face luna directs flow, happy face luna spreads flow. According to PDF, you grab the sheet flow and direct it into gully with a luna, slow it with zuni bowls and one-rock dams and then convert it from stream to sheet with another luna.
In other situations, to prevent erosion in your case, will there be other constructions in the gully?
Edit: had a brain explosion with the orientation of photo, is the water flow from bottom right to top left?
I might actually have the luna turned the wrong way, as flow comes from the lower right side and forms a gully which goes downhill on the upper left side. I guess I'll see what it does in the next rain. I might should have it turned the opposite way, what do you think?
That's right then, is it not? You are grabbing your sheet from the top of the hill, directing into a stream, and then adding another rockwork to slow it on the steep part of the gully i.e.zuni or one-rock dam, then turning it from stream to sheet at the bottom.
The photo threw me at first because my brain automatically thought the flow would go from left to right which would mean you were turning your flow into a sheet at the top of the hill. Which, I assumed, would move your erosion further down the hill as the water would reform into an eroding stream after the luna.
You must note, I'm no expert on this. Could you email drylandsolutions? Do they offer free advice or is it all bought and paid for?
I think I need another or more structures, because there is a little gully there, so maybe a couple one rock dams and then at the bottom, another media luna turned the other way. At least that's what it looks like in the pdf...It will be interesting to see how the structures behave at this very small scale.
I took the photo from that angle because otherwise my shadow would have fallen across the structure and made the pic even more confusing.
Have you thought of zai culture in amongst the junipers? Pakanohida is giving the best advice, to start high in the catchment and do small things to trap the water, all across your property. Zai is just digging holes to catch water and allow infiltration. If you get infiltration amongst the junipers then you might be able to grow support plants to help slow the water. The grassland between the junipers and house depending on it use could get trenches on contour to catch and hold water till it infiltrates. These trenches don't all have to be deep, and you can make them 5-6 feet wide dropping the level by a couple of inches. Does water come from behind the junipers? Because if so you might want to slow the water before it gets to the junipers with a berm.
Just some ideas, that can be done with nothing but a spade and a level and time. Don't forget to plant your earthworks with ground covers.
Thanks for that suggestion, John.
Here's a photo of our new berm and basin (large swale):
That looks backward to me, this is the low side of the junipers?
Water flows from the right side of the picture.
Then its perfect! And I am backward. LOL
Don't worry John, that's not the first time on this site that it has happened. I have a brain explosion regarding the same thing, water always flows from left to right!
It's ok, photos can be hard to interpret.
But honestly I HOPE I'm not putting things in backward or otherwise screwing up horribly. I think this structure might be too large for its position, but it's not easy trying to figure this out when we've been in drought for a couple years. I have to remember in the past we've had waterfalls cascading down our back hill, a wall of water coming through between our house and shop that knocked down trees and fences, and that my old vegetable garden (which is now temporarily abandoned) was under at least four inches of water.
S.O.P Its Ok I know I make mistakes, but I don't feel shame over it.
Ludi I don't think it can be too big, except the front wall is clay so its probably going to act as a dam and hold water most of the year if not forever. If forever then its not too big, as you can have fish. It might be too middling, where it acts as a dam, but not big enough to hold over till the next rains. Whatever happens there will be a way to make it positive. That's where the gardening comes in.
The other one we had made about 3 years ago doesn't hold water for longer than a few hours. It's not compacted and our soil is free-draining in spite of having a lot of clay. This structure was never intended to hold water, just slow it down and infiltrate it. Of course we won't know how it behaves until we get a big rain.
My husband borrowed the neighbor's tractor the other day and dug this swale behind the house:
It'll rain now...
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